Add unobfuscated alt code to 2020/otterness

This code was found on the author's web page about the entry and has
been added as prog.alt.c. I added the try.alt.sh script as well.

Manifest updated and rebuilt .entry.json and index.html files.

2020/otterness/.gitignore

@@ -6,6 +6,7 @@ indent
 indent.c
 indent.o
 prog
+prog.alt
 prog.orig
 !cvikl.mid
 !entertainer.mid